1. Field of the Invention
The invention relates, generally, to folders, and more specifically, to a folder having a deceleration drum with air guides.
2. Description of the Related Art
It is known in the art to provide a deceleration drum in a folding machine for slowing down signatures transported in the folding machine. Such a device is known from U.S. Pat. No. 5,452,886 to Cote et al.. Cote et al. teach a deceleration drum that is provided with a plurality of rotary grippers that positively grip signatures exiting a tape conveyor system and traveling at a high velocity and decelerates the signatures through a smooth velocity profile. In the deceleration process, the speed of the individual grippers can be controlled so as to overlap adjacent signatures for forming a shingled pile of signatures. The rotary grippers grip a leading edge of the signatures while the trailing edge is initially controlled by the tape conveyor system and later dragged alone a guide plate or a guide belt until delivered in a shingled form to an exit conveying system. Unfortunately, the trailing edges of the signatures that are dragged along the static plate or belt are apt to being marked, damaged and/or smudged.
U.S. Pat. No. 5,816,155 to Stephan teaches a printing press having printing units formed of an impression cylinder, a rubber blanket cylinder and a plate cylinder. Between the printing units a transfer drum is disposed for transferring signatures from one printing unit to the other printing unit. A guide surface member is provided around the transfer drum for assisting in transporting the signatures around the transfer drum in a contactless manner. The use of guide surface members for transporting signatures in a contactless manner is known in the art of transfer drums within the printing press but is not believed to known to be used in further processing machines (i.e. folders) disposed downstream of the printing presses. For instance, the use of guide surface members for transporting signatures is not believed to be known to be used in conjunction with deceleration drums of a folder.
It is accordingly an object of the invention to provide a deceleration drum assembly containing air guides that overcomes the herein-mentioned disadvantages of the heretofore-known devices of this general type, in which signatures are transported in a contactless manner to avoid damaging the signature in its transport path around the deceleration drum.
With the foregoing and other objects in view there is provided, in accordance with the invention, a deceleration drum assembly, containing a deceleration drum having at least one gripper for gripping a signature; and a guide surface assembly providing a fluid flow for transporting the signature in a contactless manner above the guide surface assembly.
In accordance with an added feature of the invention, the guide surface assembly contains at least one guide surface member having a surface with a plurality of nozzles formed therein. Air supply chests and fans are provided disposed below the guide surface assembly for supplying air to the nozzles. In this manner, the fans in conjunction with the nozzles can supply both blast air and suction air for controlling and transporting the signature.
In accordance with an additional feature of the invention, the guide surface assembly is formed successively of an entry region, a guide zone region and an exit region. The nozzles in the entry region and the exit region supply both blast air and suction air. The blast air prevents the signature from contacting the guide surface member and the suction air allows frictional forces to build between the signature and the guide surface member for controlling the signature. In this manner, a precise control of the signature can occur while transporting the signature. In addition, the suction air mode allows one to control the placement of the signature should the deceleration drum assembly need to be temporarily shut down in which precise placement of the signature is desirable.
In accordance with another feature of the invention, at least some of the fans in the entry region and the exit region are reversible fans for supplying the blast air and the suction air to some of the nozzles. It is further advantages if the fans are adjustable speed fans for adjusting an air flow rate.
In accordance with a further added feature of the invention, the nozzles are slit nozzles. In addition it is preferred if some of the nozzles are oriented to provide an air flow that is perpendicular to a signature travel direction for tautening the signature. Furthermore, positioning the nozzles to provide an air flow that both tautens and assists in transporting the signature is desirable.
In accordance with a further additional feature of the invention, the nozzles are disposed on the guide surface member in an array having a distribution varying in density and a distribution density of the nozzles is greatest in a middle of a signature travel path and decreases toward an edge of the signature travel path.
In accordance with a concomitant feature of the invention, the guide surface member has at least one recess formed therein and including at least one sensor disposed in the at least one recess. The at least one sensor outputting sensor data determining at least one of a height of the signature above the guide surface assembly, an air pressure under the signature, and a position of the signature in regards to the guide surface member. A control unit is provided that is connected to the sensors and to the fans for controlling the fans in response to the sensor data. Finally, it is possible to have a plurality of sensors disposed on either the guide surface member or on the deceleration drum.
Other characteristic features of the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in deceleration drum assembly containing air guides, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.